Photographic processing of a silver halide photographic material generally contains steps of development, fixing, washing and so on if the material is a black-and-white light-sensitive material, and involves steps of color development, bleaching, fixing, washing, stabilization, etc. if a color light-sensitive material is to be processed. The working solutions employed in either case have the ability to perform one or more photographic functions.
In processing a large amount of light-sensitive material, it is customary to keep the make-up and hence the performance of each working solution constant not only by compensating for the components consumed in a specific step but also by eliminating any component in the working solution which increases in amount (e.g., bromide ions in the developing solution and silver complex salts in the fixing bath). In order to compensate for the consumed component, a replenishing solution is added to a specific working solution, and for the purpose of eliminating the excess of the component which has increased in amount, part of the working solution is discarded.
Primarily for environmental and economic reasons, concerted efforts are being made by modern photofinishers to drastically reduce the use of replenishers including the washing water which is a replenisher for the washing step. Even in this modern system, the waste working solution is discharged from each of the tanks in the automatic developer and, after being guided through a drain pipe, the solution is diluted with the waste washing water for disposal in sewage or other appropriate places.
With a view to coping with limited water resources and the increased cost of water feeding and drainage and in order to provide ease in the installation of the automatic processor and to improve the working environment around the machine, photographic processing with a water-less automatic processor has been designed and is gaining commercial acceptance.
This machine performs a stabilizing step as an alternative to washing and requires no water feed/drain piping other than what is installed within the machine. It is generally understood that in this sort of photographic processing, the use of cooling water for stabilizing the temperature of working solutions is also desirably reduced. The effluent from the water-less automatic developer is comprised solely of the replenished waste working solutions and is much smaller in amount than when a washing step is included in the process. Because of this feature, the need for installing pipes for water feeding and drainage is eliminated and all of the following problems associated with the conventional types of automatic developer can be solved: a machine with water pipes is difficult to replace after installation; the machine reduces the amount of floor space available for free movement of the operator; additional costs are incurred in attaching pipes to the machine after it is installed in the proper place; and energy costs with feeding hot water are comparatively high. The water-less automatic processor is free from these disadvantages and its small size and operational simplicity will allow its use as an office machine.
However, processing with such water-less automatic processor results in the discharge of fairly large quantities of waste solutions; even in a comparatively small-scale operation, the daily effluents are no less than 10 liters for the processing of X-ray light-sensitive materials, 30 liters for platemaking light-sensitive materials, and 30 liters for color photographic materials. In the absence of external water pipes, the treatment of the effluents from the water-less automatic developer is relatively complicated; first of all, when a certain waste solution tank in the developer is filled with the waste solution, this event must be detected either with a sensor or by visual checking so as to allow for a timely replacement of the tank, and if this is not done, the waste solution will overflow the tank and foul the floor, thereby cancelling the advantages offered by the water-less automatic processor (i.e., the machine does not have to be equipped with external piping and can be installed on a clean floor or a carpeted floor). Aside from the high cost of the sensor, processing with the water-less automatic processor involves one major problem associated with aesthetic appeal in that the container for accommodating the recovered waste solution is more likely to be fouled than when the waste solution is discharged into sewage through the drain pipe.
Most of the photographic processing solutions used today contain easily oxidizable components and are liable to form tar or precipitates as a result of aerial contact during storage. If, as in the usual practice, two or more working waste solutions are recovered in the waste solution tank, the chance of oxidation or precipitation is further increased to form tar or precipitates which are deposited on the bottom or side wall of the tank and will solidify to foul or otherwise degrade the working environment. The tendency of tar formation is particularly great in waste solutions containing hydroquinones or phenidones (black-and-white developing agents), or phenylenediamine derivatives (color developing agents) and splashes of such waste solution will soil the operator's clothes or cause rashes on his skin. A waste solution containing thiosulfate ions will be oxidized to form a sulfur precipitate. If these two types of waste solution are mixed, the degree of tar formation and precipitation is even more increased, and in the presence of a certain substance such as ethylenediaminetetraacetic acid iron (III) salt, troubles such as the precipitation of iron hydroxide or oxide that will cause considerable difficulty in handling may occur.
The last, but by no means least, problem associated with the processing with the water-less automatic processor is that it discharges an aqueous solution which cannot be immediately disposed of by incineration. A processing system in which no waste washing water occurs will yield waste solutions with high BOD and COD loads which cannot be directly discharged into sewage. The most advantageous way to dispose of such waste liquors is incineration.